Methods of improving printing resolution in chain type printers

ABSTRACT

The method of this invention may be used with a chain type printer presenting a set of characters for printing and having a memory defining one of the set of characters to be printed along a series of positions constituting a print line. Such printers are adapted to be controlled by a program, for example, the printer in IBM Model 1403. Therefore, each of the customary alphanumeric printing characters of said machine is replaced by a discrete printing element having a much smaller printing surface than the customary characters. Each element is arranged in position relative to the character supporting body to print out the programmed character in one position of a matrix form of x elements in y rows. Instructions are given to the machine to choose a print character for printout of each element position within the matrix boundaries in the form of a binary coded number of eight bits. A series of N xy separate printouts provides printout over the entire matrix pattern. A matrix array of said smaller printing surfaces each element of which is printed by the selection of one coded character in a separate printout operation of the printer can form any programmed pattern such as that of a selected alphanumeric character.

United States Patet Bergeron [75] Inventor: Louis Bergeron,Ballainvilliers,

France [73] Assignee: Centre National dEtudes Spatiales,

Paris, France [22] Filed: Dec. 14, 1972 [21] Appl. No: 315,193

[30] Foreign Application Priority Data Dec. 15. 1971 France 71.45081[52] US. Cl. 101/426; 197/1 R [51] Int. Cl B41j 3/00 [58] Field ofSearch 197/1 R; 101/426 [56] References Cited UNlTED STATES PATENTS1,777,622 10/1930 OHare 197/1 3,267,852 8/1966 Gordon 3,550,148 12/1970Machler.. 3,726,379 4/1973 Isaac 197/1 Primary Examiner-Edgar S. BurrAssistant Examiner-R. T. Rader Attorney. Agent, or Firm-A. W Breiner[57] ABSTRACT The method of this invention may be used with a chain typeprinter presenting a set of characters for printing and having a memorydefining one of the set of characters to be printed along a series ofpositions constituting a print line. Such printers are adapted to becontrolled by a program, for example, the printer in IBM Model 1403.Therefore, each of the customary alphanumeric printing characters ofsaid machine is replaced by a discrete printing element having a muchsmaller printing surface than the customary characters. Each element isarranged in position relative to the character supporting body to printout the programmed character in one position of a matrix form of xelements in y rows. Instructions are given to the machine to choose aprint character for printout of each element position within the matrixboundaries in the form of a binary coded number of eight bits. A seriesof N=xy separate printouts provides printout over the entire matrixpattern. A matrix array of said smaller printing surfaces each elementof which is printed by the selection of one coded character in aseparate printout operation of the printer can form any programmedpattern such as that of a selected alphanumeric character.

2 Claims, 4 Drawing Figures PATENTED HAY 2 0 I975 FIG. :7

METHODS OF IMPROVING PRINTING RESOLUTION IN CHAIN TYPE PRINTERS Thepresent invention relates to the printing art and more particularly to amethod of printing documents such as weather charts for instance and tomeans for performing the same. The object of this method is to increasethe detail definition on documents printed, by comparison with documentsprinted by the prior methods.

The invention is based on the observation that with prior art printingmachines the degree of resolution of the traces produced by printing isnot very high and that it would be possible to substantially improveresolution without basically modifying the printing machine.

The methods for achieving this objective include recourse to a printingmachine of a type well known per se but preferably a chain typehigh-speed printer equipped with a memory and controllable by apreestablished program. In accordance with the invention, the customaryprinting characters on such a machine are replaced by a numbermanifestly larger of ele ments having printing surfaces which are muchsmaller than those of the customary characters and are differentlydisposed on the character body to reside in a set of positions forforming a character as a matrix set of the elements. Correspondinginstructions are given to the machine to print each element position inthe character matrix in order to achieve the desired highdefinitionprinting.

In the printing method according to this invention a printer of knowntype is utilized and its customary printing characters such as in a 135character alphameric font are replaced by a set printing elements havinga much smaller surface to each print out one of a set of matrixpositions replacing the former character dimensions. Correspondinginstructions are given to the printer to print out the set of printingelement positions to form a character matrix. The method may comprisethe following steps:

a. the place occupied by each conventional character is divided up intoa number N x y of areas with x lines and 3' columns;

b. there is assigned to each area a number p of different possible sizesfor the area of the printing dot' or spot accomodated therein;

c. the printer is provided with p.N differently arranged printingsurfaces (dots or spots); and

d. the printer is so controlled as to enable it to print N times on eachline and to cause the entirety of said area to be printed with theselected dot or spot array corresponding to the character or printpatterns to be made.

The invention will be more clearly understood from the description whichfollows with reference to the accompanying non-limitative exemplarydrawing, in which:

FIG. 1 shows the manner of dividing up a conventional character inaccordance with the invention.

FIG. 2 depicts an example of a print to be made.

FIG. 3 shows the printer characters to be used to obtain the print inFIG. 2.

FIG. 4 shows examples of possible dot shapes in accordance with a morerefined aspect of the invention.

For a preferred embodiment of this invention, consideration is firstgiven to a standard printer character (FIG. I) of rectangular shapemeasuring approximately 2.5mm by 3.3mm (or more precisely one-tenth inchby one-eighth inch). As shown, this character can be divided into amatrix of four times five square areas or compartments, each compartmentbeing therefore substantially 0.63mm (1/40 inch) square. A dot or otherelement shape can be provided in each of these squares whereby to obtainvery-high-definition printing.

It will first be assumed that the shape of this dot is circular. Inaccordance with the invention, the size of the dot may vary. Preferably,in the practical example herein considered, the size of the dots iscaused to vary in discrete values to form a set of seven possible dots".In the event of circular dots being used, their diameter in millimetresmay be increased in the following steps:

Diametertmm) 0.08 0.17 0.26 0.34 0.43 0.5] 0.60 Dot No. I 2 3 4 5 6 7This being so, the printing machine to be utilized for instance a chaintype line printer equipped with a memory or storage device and capableof being controlied by a programwill have to have a total number ofdistinct characters equal to 4 X 5 X 7 140 different printing elements.One example of such a printer is the IBM 1403, which has normallycharacters.

Reference to FIG. 3 shows four of these printing elements C C C C allcorresponding to the upper printing line which is assumed to be formedas shown in FIG. 2. Printing element C prints a dot with compartment aduring a first pass by the printer, after which element C prints a dotwith compartment [2 during a second pass, element C prints withcompartment 0 during a third pass and element C, with compartment dduring a fourth pass.

More generally, it will be seen that if a standard character has beendivided in N x y compartments (x being the number of lines and y thenumber of col umns) and if there has been assigned to each compartment anumber p of possible dot surface sizes, then the printer must have pNprinting elements and the instruction program must provide for N passeswithout vertical displacement of the paper.

It is to be noted that the weight and hence the inertia of the printingelements may remain of the same order as before even though the printingsurface is very small. Therefore, because of the increased printingpressure per unit area, strong paper must be used for the printoutunless the printer includes means for suitably ad justing the strikingpressure.

The position of a dot on its rectangular support can be coded (in theoctal system for example). Thus, if the different compartments arenumbered:

1 2 3 4 5 6 7 10 ll l2 13 14 l5 l6 17 20 21 22 23 24 and if the dotsizes are coded from O to 7, where 0 corresponds to a blank space (noprinting), then each element print will be coded by a three-positionoctal number in which the first two positions determine the location ofthe dot on its support and the third its size (or signal level). Such acode will comprise eight binary bits.

For example, level No. 5 in location 13 will be coded 135 in octal or O1011 101 in binary.

This and other similar data relating to the different dots can be storedin the memory and used to control the printer.

In the present invention it is also possible to conceive of a morerefined aspect in the display of the dots, as portrayed in FIG. 4. Theunderlying principle here consists in relating the apparent shape of theprint spot to its level. This permits direct readings of the signalintensity, which could otherwise be more or less difficult to appraisefrom the size of the spot surface. At the same time, in the case of aweather chart for example, there will be surfaces that encompass aconsiderable number of dots all of the same level, after the fashion ofparallel-oriented small shadings or punctuated blocks, and it will beeasy to distinguish between two contiguous areas of different intensity.

It goes without saying that changes and substitutions may be made in theexemplary embodiments hereinbefore described without departing from thescope of the invention.

I claim:

1. The method of printing patterns of variable resolution with a printerhaving a font of characters to be printed out in at least one printposition of known dimensions, said printer being equipped with a memoryand controllable by a printing program, comprising the steps of 1.replacing the font of characters with a set of printing elements eachlocated in a discrete one of a number N of matrix positions within saiddimensions,

2. providing for each of said N matrix positions a plurality of elementsof different size,

3. identifying each matrix element including those elements of differentsize with a separate coded representation to be stored in said memory,

4. controlling the printer to print out N times at each print positionto form a print out pattern at said N matrix positions, and

5. identifying a print pattern of said elements to be printed out ateach said print position by a corresponding set of said codedrepresentations stored in said memory designating the size of theelement to be printed out in each of said N matrix positions.

2. The method of printing defined in claim 1 including the step ofproviding for each element of different size a distinctive shape.

1. The method of printing patterns of variable resolution with a printerhaving a font of characters to be printed out in at least one printposition of known dimensions, said printer being equipped with a memoryand controllable by a printing program, comprising the steps of 1.replacing the font of characters with a set of printing elements eachlocated in a discrete one of a number N of matrix positions within saiddimensions,
 2. providing for each of said N matrix positions a pluralityof elements of different size,
 3. identifying each matrix elementincluding those elements of different size with a separate codedrepresentation to be stored in said memory,
 4. controlling the printerto print out N times at each print position to form a print out patternat said N matrix positions, and
 5. identifying a print pattern of saidelements to be printed out at each said print position by acorresponding set of said coded representations stored in said memorydesignating the size of the element to be printed out in each of said Nmatrix positions.
 2. The method of printing defined in claim 1 includingthe step of providing for each element of different size a distinctiveshape.
 2. providing for each of said N matrix positions a plurality ofelements of different size,
 3. identifying each matrix element includingthose elements of different size with a separate coded representation tobe stored in said memory,
 4. controlling the printer to print out Ntimes at each print position to form a print out pattern at said Nmatrix positions, and
 5. identifying a print pattern of said elements tobe printed out at each said print position by a corresponding set ofsaid coded representations stored in said memory designating the size ofthe element to be printed out in each of said N matrix positions.